Infections in horses encompass a range of diseases caused by various pathogens, including bacteria, viruses, fungi, and parasites. These infections can affect different systems within the horse, such as the respiratory, gastrointestinal, and integumentary systems, leading to a variety of clinical signs depending on the pathogen and the severity of the infection. Common infectious diseases in horses include equine influenza, strangles, and equine herpesvirus. Diagnosis often involves clinical examination, laboratory testing, and sometimes imaging, to identify the causative agent and assess the extent of the disease. Treatment strategies may include antimicrobial therapy, supportive care, and preventive measures such as vaccination and biosecurity practices. This page aggregates peer-reviewed research studies and scholarly articles that explore the pathogenesis, diagnosis, treatment, and prevention of infectious diseases in equine populations.
Cabasso VJ, Nieman R, Schroeder DD, Hok KA, Louie RE, Mozen MM.A horse has been immunized with Australia antigen (Au/SH) purified 20-fold by a procedure employing gel filtration of Cohn fraction IV derived from an Au/SH-positive human plasma pool. Hyperimmunization was initiated by the intramuscular injection of 20 ml of a mixture of equal parts of purified Au/SH and complete Freund's adjuvant. The 20-ml volume was divided into four 5-ml doses, two of which were administered on each side of the horse's neck. Booster doses of antigen alone were given as follows: 10 ml intravenously 30 days later and 5 ml intramuscularly on each of days 77 and 205. Au/SH an...
Lawrence WC.Autoradiographic analyses of deoxyribonucleic acid (DNA) synthesis in randomly growing KB cell cultures infected with equine abortion virus (EAV) suggested that viral DNA synthesis was initiated only at times that coincided with the entry of noninfected control cells into the S phase of the cell cycle. Synchronized cultures of KB cells were infected at different stages of the cell cycle, and rates of synthesis of cellular and viral DNA were measured. When cells were infected at different times within the S phase, viral DNA synthesis was initiated 2 to 3 hr after infection. However, when cells ...
Gruber J.Purified and concentrated Venezuelan equine encephalitis (VEE) virus derived from tissue cultures, rendered noninfectious by ionizing radiation with retention of in vitro serological activity, also retained a high level of immunogenicity. In mice, fluid vaccines afforded excellent protection against lethal challenge with homologous Trinidad strain VEE virus. A direct relationship was observed between concentration of vaccine or number of injections and survival. One intraperitoneal inoculation of undiluted vaccine protected essentially all mice challenged 21 days later with 100,000 mouse intra...
Henderson BE, Chappell WA, Johnston JG, Sudia WD.Henderson, B. E., W. A. Chappell, J. G. Johnston, Jr. and W. D. Sudia (CDC, Atlanta, Ga. 30333). Experimental Infection of horses with three strains of Venezuelan equine encephalomyelitis virus. I. Clinical and virological studies. Amer J Epidem 93: 194–205, 1971.—Clinical effect, viremias and antibody responses were compared in horses inoculated with the following strains of Venezuelan equine encephalomyelitis (VEE) virus: Fe3-7C, isolated from Culex (Melano-conion) spp. mosquitoes collected In 1963 in the Florida Everglades; TC-83, the Fort Detrick live, attenuated vaccine strain; and GJ...
Nakajima H, Ushimi C.Antigenicity of purified equine infectious anemia (EIA) virus was examined by immunodiffusion against sera obtained from horses experimentally infected with EIA virus. The purified virus reacted with the infected horse serum, and virus-specific precipitating antibody was demonstrated. Furthermore, it was found that purified EIA virus reacted against the serum of horses infected with all strains of EIA virus which were antigenically different from one another. From the result, group-specific components of the virus rather than strain-specific ones were considered to be involved in the reaction....
Pocurull DW, Gaines SA, Mercer HD.Salmonella cultures were obtained from outbreaks of animal disease from 37 states and 1 territory. They were screened for resistance to 11 antimicrobial drugs. Of the 1,251 strains studied, 935 were resistant to one or more of these agents. The three most common resistance patterns were ampicillin, dihydrostreptomycin, sulfamethoxypyridazine, tetracycline; ampicillin, dihydrostreptomycin, sulfamethoxypyridazine; dihydrostreptomycin, sulfamethoxypyridazine, tetracycline. Resistance transfer was demonstrated on 267 multiply resistant cultures, of which 181 were able to transfer all or part of th...
Dória RGS, Freitas SH, Laskoski LM, Arruda LP, Shimano AC.Surgical site infection of abdominal incisions is an important complication after laparotomy with increased risk of incisional hernia formation in horses. This study aims to evaluate the healing process of abdominal incisions and correlate peritonitis with the occurrence of surgical site infection and incisional hernias. Nine horses underwent standardized laparotomy, intestinal exploration, and induced septic peritonitis. Standardized relaparotomy was performed two (n = 3), four (n = 3), and six (n = 3) months later to evaluate the abdominal cavity for adhesions and to collect the sutured v...
Klingeborn B.Twelve mares were vaccinated with attenuated equine abortion virus (EAV) strain RAC-H. Two nonvaccinated mares served as controls. In at least three mares the vaccination appeared to coincide with a natural infection. This was indicated by characterization of the EAV isolated from nasal secretions of six vaccinated mares, a nonvaccinated control, and also from the lung, spleen, and liver of a fetus aborted by a vaccinated mare. The relative sensitivity of the isolated EAV to dithiothreitol was used to distinguish the RAC-H strain and wild-type virus. Of the 10 EAV isolates, four were recognize...
Legrottaglie R, Agrimi P.Electrophoretic analysis in polyacrylamide gel (PAGE) of the equine rotavirus 106/88/LI/EQ, isolated from the diarrhea of an 18 day old foal was compared to the bovine strain NCDV. There was a notable difference in the migration of some segments of the viral RNA. Bands 2 and 3 of the equine rotavirus comigrated while there was a clear separation of segments 7, 8 and 9. Moreover, the migration of segments 1, 4 and 5 revealed a lower molecular weight than the corresponding segments of NCDV.
Kay AT, Hunt RJ, Rodgerson DH, Spirito MA, Santschi EM, Payne RJ.To describe the characteristics of osteomyelitis lesions of the patella and to report short- and long-term outcome after treatment in 8 foals. Methods: Retrospective case series. Methods: Foals (n = 8). Methods: Medical records (2003-2007) and radiographs of foals that had osteomyelitis of the patella were reviewed. Inclusion criteria included clinical, radiographic, and surgical findings consistent with osteomyelitis of the patella, and a long-term follow-up of >15 months. Information acquired included signalment, hematologic and serum biochemical profile results, clinical and radiographic si...
Heath SE, Geor RJ, Tabel H, McIntosh K.An enzyme-linked immunosorbent assay (ELISA) was developed for use in horses to determine serum titers of antibodies of the immunoglobulin classes IgA, IgG, and IgM to Streptococcus equi M-like protein and culture supernatant protein antigens. Serum antibodies were determined in 28 adult horses, including 9 horses with recent S. equi infections, 17 horses without known exposure to S. equi, but without a history of respiratory disease in the preceding 4 months, and 2 horses with clinical purpura hemorrhagica. Serum IgA titers to culture supernatant protein antigen were highest in recently infec...
VÄ•znÃk Z, Svecová D, PospÃsil L, DiblÃková I.Frequency of elementary and reticular chlamydial bodies was investigated by direct immunofluorescence tests in ejaculates collected from 52 men, 60 stallions, 42 bulls, and 66 boars using the kits of Progen Biotechnic GmbH and the microscope Labophot-2 Nikon. At the same time, qualitative semen tests, including ejaculate volume, sperm motility, percentage of live and dead sperms and morphological' analyses (VÄ•znÃk and Svecová, 1992) were done. Repeatability of the findings was checked in a group of nine bulls housed at the institute and sampled at weekly intervals for 3 to 4 months (Tab. 1)...
Acland HM, Allen PZ, Kenney RM.Twenty-three of 24 mares were infected experimentally with contagious equine metritis organisms by intrauterine inoculation, and killed 2-116 days later. From mares killed within 14 days after infection the organism could be recovered from many sites in the uterus, and most sites in the cervix, a few sites in the vagina and oviduct and from one clitoral sinus. At this time the endometrial folds were swollen and there were 10-20 ml of fluid in the uterus. In mares killed after 14 days, the organism was recovered from the ovarian surface (1 mare), oviduct (4 mares), uterus (2 mares) and the clit...
Morris CM, Field HJ.Tissue specimens obtained from equine herpesvirus-1 (EHV-1), subtype 1-infected aborted foetuses were analysed for the presence of virus DNA by means of Southern blot and dot blot hybridisations. The specificity of the methods was confirmed although the sensitivity was inferior to classical techniques such as virus isolation. However, the possibility of detecting the state of the virus DNA and the ability to distinguish between subtypes were important features, and the dot blot method was shown to have potential for a rapid diagnostic test. This report demonstrates some potential practical app...
Pozio E, Celano GV, Sacchi L, Pavia C, Rossi P, Tamburrini A, Corona S, La Rosa G.Epidemiological investigations conducted during 10 trichinellosis outbreaks between 1975 and 1994 showed that horse-meat was the probable source of infection. Though hundreds of thousands of horses have been examined at abattoirs in America and Europe to detect Trichinella infection by artificial digestion or trichinelloscopy, an infected horse has never been detected during routine analysis, which consists of examining 1 g of tissue muscle from the diaphragm. In November 1996, a naturally infected horse imported from Romania was detected in Southern Italy. The parasite was identified as Trich...
Paweska JT, Henton MM, van der Lugt JJ.Clinical, virological and serological responses were evaluated in 10 pregnant mares after different challenge exposures to the asinine-94 strain of equine arteritis virus (EAV). The outcome of maternal infection on the progeny was also investigated. Mares were inoculated intranasally (n = 4), intramuscularly (n = 2), intravenously (n = 1), or contract-exposed (n = 3). All inoculated mares developed pyrexia, 5 showed mild clinical signs related to EAV infection and 2 remained asymptomatic. Viraemia was detected in all the inoculated animals and shedding of virus from the respiratory tract occur...
Moll HD, Schumacher J.A 2-year-old Tennessee Walking Horse colt was admitted for evaluation of signs of abdominal pain, inappetence, and constipation of 5 days' duration. Two days prior to the onset of signs, the owner had cut the sacrococcygeal muscles as part of a tail-setting procedure. On examination, the horse was febrile and lethargic, and intestinal sounds were not heard on auscultation. Results of peritoneal fluid analysis were indicative of peritonitis. The horse continued to deteriorate and died despite treatment with antimicrobials, flunixin meglumine, and balanced electrolyte solution. At necropsy, the ...
Page AE, Stills HF, Horohov DW.Multiple hypotheses into the age-based susceptibility of animals to Lawsonia intracellularis exist, including the decline of passively acquired antibodies. Objective: To determine whether the decline in passively acquired antibodies in horses is responsible for the age predilection of equine proliferative enteropathy (EPE). Additional objectives included examination of various risk factors for the development of EPE as well as the determination of naturally occurring attack rates for clinical and subclinical EPE. Methods: Prospective, multifarm field study. Methods: A total of 369 mare and f...
Büchi S, Waelchli RO, Corboz L, Gygax AP, Wälti RJ.In the mare, natural breeding is associated with bacterial contamination of the reproductive tract. The purpose of this study was to examine postcoital bacterial contamination and the resulting inflammatory response of the uterus. Uterine swabs for bacteriological and cytological examination were obtained from 80 mares. Each mare was sampled once between 4 and 69 hours postbreeding. In mares which did not conceive, sampling was repeated at the following estrus. The findings were compared with those obtained prior to breeding and correlated with the breeding outcome. Bacteria were cultured from...
Carrier SP, Boulanger P, Bannister GL.The comparative values of the direct, the indirect complement-fixation and the agar-gel immunodiffusion tests were assessed for the diagnosis of equine infectious anemia. Antibodies were detected on the agar-gel immunodiffusion test as early as 18 days post-inoculation in the serums of experimentally infected horses and were readily detectable in all the subsequent bleedings. Complement-fixing antibodies, demonstrable by the direct method, were detected commencing about the same time. However, these were not long-lasting and were replaced by the non-complement-fixing antibodies demonstrable by...
Ahmed SM, Broad SC, Edington N.Sera from two sibling groups of ponies experimentally infected with Equid herpesvirus 1 or 4 (EHV-1 or 4) were used to investigate which viral polypeptides (VPs) of EHV-1 and EHV-4 were recognised. Recognition was detected as early as 8 d.p.i. and thereafter. The polypeptides of EHV-1 (labelled with 35S-methionine) immunoprecipitated (IIP) by sera from both groups had Mr of 148, 138, 123, 117, 110, 77-79, 70, 55, 49-50, 47, 40 and 35-37 kDa respectively. Of these VP148K (VP9 nucleocapsid) gave the maximum precipitation, followed by 117 and 77-79 kDa. The latter were confirmed by monoclonal ant...
Page AE, Stills HF, Chander Y, Gebhart CJ, Horohov DW.Lawsonia intracellularis is the causative agent of equine proliferative enteropathy (EPE), a disease for which no large-scale seroprevalence studies have been conducted. Objective: To validate and use an equine-specific enzyme-linked immunosorbent assay (ELISA) for L. intracellularis to determine the seroprevalence of L. intracellularis on numerous farms. Methods: An ELISA, in which purified antigen was used, was adapted from previous work in swine. A total of 337 Thoroughbreds from 25 central Kentucky farms were enrolled and monthly serum samples collected from August 2010 to January/February...
Routledge NB, Harris RC, Harris PA, Naylor JR, Roberts CA.The variation over 24 h of plasma glutamine concentration in nonexercising horses was studied in 3 Thoroughbreds (TB) fed at 1600 h and 0700 h. This indicated a small but regular change associated with feeding. Starting at a mean of 482 mumol/l at 1600 h the concentration increased to 522 mumol/l at 2000 h, falling to 476 mumol/l at 1600 h and increasing again to 525 mumol/l at 2000 h. 'Normal' values were established in 19 part-bred TB horses, lacking clinical signs or remarkable pathology and in light training, by sampling weekly at 1000 h over a 10 week period. The mean concentration was 49...
Bello TR.Antiparasitic efficacy of ivermectin against migrating Gasterophilus intestinalis was evaluated in 36 treated and 24 nontreated (n = 12) or vehicle-treated (n = 12) ponies experimentally and naturally infected with G intestinalis and naturally infected with G nasalis. Each pony was experimentally infected with 500 G intestinalis 1st instars in 2 divided doses on days -14 and -7 before treatment. On day 0, ivermectin was administered at the rate of 200 micrograms/kg of body weight by IV (n = 12) or IM injection (n = 12) or given as an oral paste (n = 12). Ponies were euthanatized and necropsied...
Ousey JC, Rossdale PD, Cash RS, Worthy K.Multiparous pregnant mares, on two studfarms, were studied following natural challenge with equid herpesvirus-1 (EHV-1). They were divided into three groups according to serum complement fixation titres: Group A (N = 11) were not challenged and delivered normal foals; Group B (N = 13) were challenged but delivered normal foals; Group C (N = 23) were challenged and delivered infected foals which were stillborn or lived for less than 31 h. In Groups A and B mean (+/- s.d.) gestational age at delivery was 343 (+/- 8) and 339 (+/- 8) days respectively, whereas in Group C it was significantly (P le...
Bennett D.The gross and histological features of multiple bone infection in two foals are described. In both cases the lesions were confined to the region of the growth plate. Bone and, in some cases, growth plate cartilage destruction has occurred associated with an extensive inflammatory cell infiltration. The significance of the pathological observation is discussed in relation to the pathogenesis of bone infection in the foal.
Furr MO.Neurologic disease of foals is a diagnostic and therapeutic challenge for veterinarians. Disease conditions such as neonatal encephalopathy are seen as well as developmental and congenital defects, bacterial infections, and trauma. Neonatal encephalopathy can be considered a "syndrome" with a variety of causes resulting in a similar clinical presentation. These causes can be categorized as maladaptation, hypoxic/ischemic encephalopathy, and metabolic abnormalities, all leading to signs of cerebral and brainstem disease. Spinal cord signs may occasionally be seen, but these signs are usually ov...
Löhr CV, Polster U, Kuhnert P, Karger A, Rurangirwa FR, Teifke JP.Actinobacillus suis-like organisms (ASLOs) have been isolated from the genital, respiratory, and digestive tracts of healthy adult horses, horses with respiratory disease, and septic foals. Two foals with congenital hypothyroidism-dysmaturity syndrome from separate farms developed ASLO infection. At necropsy, both had contracted carpal flexor tendons, thyroid hyperplasia, and thrombotic and necrotizing mesenteric lymphangitis and lymphadenitis; one foal also had mandibular prognathism. Numerous ASLOs were isolated from tissues from both foals, including intestine. Biochemical testing and mass ...
The importance of the horse industry to the economy of the United States and the impact of parasitic infections on the industry are well documented. However, contemporary research activity on internal parasites of horses has not kept pace with growth of the horse population. Parasitic infections are a major facet of enteritis and colic in horses. Parasites are also associated with poor growth and development, respiratory tract disease, dermatitis, and CNS lesions. Babesia infections remain a threat to horses imported from some regions of the world. Most research activity has dealt with the dev...
Bauck AG, Nelson E, McLain A, Cock G, Sanchez LC, Freeman DE.To describe a modified celiotomy to improve access to cranial abdominal structures in horses. Methods: Four horses. Methods: Short case series. Methods: Three horses with gastric impactions were treated with gastrotomies. One horse was treated for a diaphragmatic hernia with herniorrhaphy and mesh augmentation. In all horses, the ventral midline celiotomy was modified cranially with a J-incision through the body wall, along the paracostal arch. Results: The only surgical complications were midline incisional infections in all horses. Three of the four horses had good long-term outcomes; the re...
Hill WK, Weenink-Van Loon CD.Report on the results of serological studies on the species Leptospira interrogans in cattle (19,607), swine (6,348), dogs (182) and horses (88) from the Netherlands during the period from 1969 to 1974. Living cultures of the serotypes of pomona, icterohaemorrhagiae, canicola, guidae (Tarassovi serological group), grippotyphosa and sejroe were used as antigen in the micro-agglutination test. The numerical findings showed that antibodies to serotypes of the species Leptospira interrogans were present in 7.67 per cent of the cattle, 22.21 per cent of the pigs, 36.81 per cent of the dogs and 92.0...
Boswinkel M, Sloet van Oldruitenborgh-Oosterbaan MM.Infection with Rhodococcus equi is an important cause of pneumonia in foals, but other organ systems may also be affected. The intracellular presence of R. equi and the formation of granulomatous and suppurative inflammatory tissue mean that prolonged treatment is needed. The pharmacological properties of the combination of erythromycin and rifampicin have improved the survival of foals infected with R. equi; however, erythromycin can cause adverse reactions in foals and mares, which has prompted the search for alternative therapies. The combination of azithromycin or clarithromycin with rifam...
Darenius K.Fifteen mares which had each lost their pregnancies 2 to 8 times during the preceding 6 years were used in a study comprising 1 or 2 breeding seasons for each mare. During the research period all 15 mares conceived and 10 of the mares had normal pregnancies in the 1st experimental year. Five mares resorbed/aborted once or twice during the 1st year. This was followed by a pregnancy that terminated in a live foal. Histopathological examinations of uterine biopsies showed a wide range of histopathological conditions, from absence of changes excessive for the mare's age and parity to the most seve...
Biasutti S, Dart AJ, Dart CM, Uquillas E, Jeffcott LB.A newborn foal was referred for evaluation because it had not passed meconium, despite the administration of four enemas. Abdominal radiographs and ultrasound scans showed generalised gaseous distension of the intestine and there was no observable meconium in the colon. Positive contrast colography showed contrast medium extending to the transverse colon. An exploratory laparotomy confirmed the absence of the left and right dorsal colon and the pelvic and diaphragmatic flexures. An end-to-side anastomosis of the left ventral colon to the midpoint of the small colon was performed. The foal reco...
